Powder Metallurgy
Powder metallurgy is a well-known technology. Crude forms of this technology were practiced in ancient Egypt as early as 3000 BC. This prior art process normally consists of four basic steps:
1. Producing a fine powder. PA1 2. Mixing the powder and preparing the mixture for use. PA1 3. Pressing the mixture into a desired shape. PA1 4. Heating (sintering) the shape at a desired temperature.
The pressing and sintering operations of powder metallurgy are of special importance. The pressing and repressing greatly affect the density of the product, which has a direct relationship to the strength properties. Sintering promotes bonding of the powder particles, with densification resulting in a single piece of material with good mechanical properties. Sintering of metals and some compounds usually is done in a controlled, inert or reducing atmosphere, while oxide ceramics are sintered in air. Many products having complex shapes can be produced at relatively low cost because subsequent machining steps are either minimal or are eliminated all together.